// This is an open source non-commercial project. Dear PVS-Studio, please check it.
// PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com

// ReSharper disable CheckNamespace
// ReSharper disable CommentTypo
// ReSharper disable IdentifierTypo
// ReSharper disable InconsistentNaming
// ReSharper disable UnusedMember.Global

/*
 * Ars Magna project, http://arsmagna.ru
 */

#region Using directives

using System.Text;

#endregion

#nullable enable

namespace PdfSharpCore.Pdf.Internal;

/// <summary>
/// An encoder for PDF AnsiEncoding.
/// </summary>
public sealed class AnsiEncoding
    : Encoding
{
    /// <summary>
    /// Gets the byte count.
    /// </summary>
    public override int GetByteCount
        (
            char[] chars,
            int index,
            int count
        )
    {
        return count;
    }

    /// <summary>
    /// Gets the bytes.
    /// </summary>
    public override int GetBytes
        (
            char[] chars,
            int charIndex,
            int charCount,
            byte[] bytes,
            int byteIndex
        )
    {
        var count = charCount;
        for (; charCount > 0; byteIndex++, charIndex++, charCount--)
        {
            bytes[byteIndex] = (byte) UnicodeToAnsi (chars[charIndex]);
        }

        return count;
    }

    /// <summary>
    /// Gets the character count.
    /// </summary>
    public override int GetCharCount (byte[] bytes, int index, int count)
    {
        return count;
    }

    /// <summary>
    /// Gets the chars.
    /// </summary>
    public override int GetChars (byte[] bytes, int byteIndex, int byteCount, char[] chars, int charIndex)
    {
        for (var idx = byteCount; idx > 0; byteIndex++, charIndex++, idx--)
        {
            chars[charIndex] = AnsiToUnicode[bytes[byteIndex]];
        }

        return byteCount;
    }

    /// <summary>
    /// When overridden in a derived class, calculates the maximum number of bytes produced by encoding the specified number of characters.
    /// </summary>
    /// <param name="charCount">The number of characters to encode.</param>
    /// <returns>
    /// The maximum number of bytes produced by encoding the specified number of characters.
    /// </returns>
    public override int GetMaxByteCount (int charCount)
    {
        return charCount;
    }

    /// <summary>
    /// When overridden in a derived class, calculates the maximum number of characters produced by decoding the specified number of bytes.
    /// </summary>
    /// <param name="byteCount">The number of bytes to decode.</param>
    /// <returns>
    /// The maximum number of characters produced by decoding the specified number of bytes.
    /// </returns>
    public override int GetMaxCharCount (int byteCount)
    {
        return byteCount;
    }

    /// <summary>
    /// Indicates whether the specified Unicode character is available in the ANSI code page 1252.
    /// </summary>
    public static bool IsAnsi1252Char (char ch)
    {
        if (ch < '\u0080' || ch is >= '\u00A0' and <= '\u00FF')
        {
            return true;
        }

        switch (ch)
        {
            case '\u20AC':
            case '\u0081':
            case '\u201A':
            case '\u0192':
            case '\u201E':
            case '\u2026':
            case '\u2020':
            case '\u2021':
            case '\u02C6':
            case '\u2030':
            case '\u0160':
            case '\u2039':
            case '\u0152':
            case '\u008D':
            case '\u017D':
            case '\u008F':
            case '\u0090':
            case '\u2018':
            case '\u2019':
            case '\u201C':
            case '\u201D':
            case '\u2022':
            case '\u2013':
            case '\u2014':
            case '\u02DC':
            case '\u2122':
            case '\u0161':
            case '\u203A':
            case '\u0153':
            case '\u009D':
            case '\u017E':
            case '\u0178':
                return true;
        }

        return false;
    }

    /// <summary>
    /// Maps Unicode to ANSI code page 1252.
    /// </summary>
    public static char UnicodeToAnsi (char ch)
    {
        if (ch < '\u0080' || ch is >= '\u00A0' and <= '\u00FF')
        {
            return ch;
        }

        switch (ch)
        {
            case '\u20AC':
                return '\u0080';

            case '\u0081':
                return '\u0081';

            case '\u201A':
                return '\u0082';

            case '\u0192':
                return '\u0083';

            case '\u201E':
                return '\u0084';

            case '\u2026':
                return '\u0085';

            case '\u2020':
                return '\u0086';

            case '\u2021':
                return '\u0087';

            case '\u02C6':
                return '\u0088';

            case '\u2030':
                return '\u0089';

            case '\u0160':
                return '\u008A';

            case '\u2039':
                return '\u008B';

            case '\u0152':
                return '\u008C';

            case '\u008D':
                return '\u008D';

            case '\u017D':
                return '\u008E';

            case '\u008F':
                return '\u008F';

            case '\u0090':
                return '\u0090';

            case '\u2018':
                return '\u0091';

            case '\u2019':
                return '\u0092';

            case '\u201C':
                return '\u0093';

            case '\u201D':
                return '\u0094';

            case '\u2022':
                return '\u0095';

            case '\u2013':
                return '\u0096';

            case '\u2014':
                return '\u0097';

            case '\u02DC':
                return '\u0098';

            case '\u2122':
                return '\u0099';

            case '\u0161':
                return '\u009A';

            case '\u203A':
                return '\u009B';

            case '\u0153':
                return '\u009C';

            case '\u009D':
                return '\u009D';

            case '\u017E':
                return '\u009E';

            case '\u0178':
                return '\u009F';
        }

        return '\u00A4'; // Char 164 is ANSI value of '�'.
    }

    /// <summary>
    /// Maps WinAnsi to Unicode characters.
    /// </summary>
    static readonly char[] AnsiToUnicode = // new char[/*256*/]
    {
        //          00        01        02        03        04        05        06        07        08        09        0A        0B        0C        0D        0E        0F
        /* 00 */ '\u0000', '\u0001', '\u0002', '\u0003', '\u0004', '\u0005', '\u0006', '\u0007', '\u0008', '\u0009', '\u000A', '\u000B', '\u000C', '\u000D', '\u000E', '\u000F',
        /* 10 */ '\u0010', '\u0011', '\u0012', '\u0013', '\u0014', '\u0015', '\u0016', '\u0017', '\u0018', '\u0019', '\u001A', '\u001B', '\u001C', '\u001D', '\u001E', '\u001F',
        /* 20 */ '\u0020', '\u0021', '\u0022', '\u0023', '\u0024', '\u0025', '\u0026', '\u0027', '\u0028', '\u0029', '\u002A', '\u002B', '\u002C', '\u002D', '\u002E', '\u002F',
        /* 30 */ '\u0030', '\u0031', '\u0032', '\u0033', '\u0034', '\u0035', '\u0036', '\u0037', '\u0038', '\u0039', '\u003A', '\u003B', '\u003C', '\u003D', '\u003E', '\u003F',
        /* 40 */ '\u0040', '\u0041', '\u0042', '\u0043', '\u0044', '\u0045', '\u0046', '\u0047', '\u0048', '\u0049', '\u004A', '\u004B', '\u004C', '\u004D', '\u004E', '\u004F',
        /* 50 */ '\u0050', '\u0051', '\u0052', '\u0053', '\u0054', '\u0055', '\u0056', '\u0057', '\u0058', '\u0059', '\u005A', '\u005B', '\u005C', '\u005D', '\u005E', '\u005F',
        /* 60 */ '\u0060', '\u0061', '\u0062', '\u0063', '\u0064', '\u0065', '\u0066', '\u0067', '\u0068', '\u0069', '\u006A', '\u006B', '\u006C', '\u006D', '\u006E', '\u006F',
        /* 70 */ '\u0070', '\u0071', '\u0072', '\u0073', '\u0074', '\u0075', '\u0076', '\u0077', '\u0078', '\u0079', '\u007A', '\u007B', '\u007C', '\u007D', '\u007E', '\u007F',
        /* 80 */ '\u20AC', '\u0081', '\u201A', '\u0192', '\u201E', '\u2026', '\u2020', '\u2021', '\u02C6', '\u2030', '\u0160', '\u2039', '\u0152', '\u008D', '\u017D', '\u008F',
        /* 90 */ '\u0090', '\u2018', '\u2019', '\u201C', '\u201D', '\u2022', '\u2013', '\u2014', '\u02DC', '\u2122', '\u0161', '\u203A', '\u0153', '\u009D', '\u017E', '\u0178',
        /* A0 */ '\u00A0', '\u00A1', '\u00A2', '\u00A3', '\u00A4', '\u00A5', '\u00A6', '\u00A7', '\u00A8', '\u00A9', '\u00AA', '\u00AB', '\u00AC', '\u00AD', '\u00AE', '\u00AF',
        /* B0 */ '\u00B0', '\u00B1', '\u00B2', '\u00B3', '\u00B4', '\u00B5', '\u00B6', '\u00B7', '\u00B8', '\u00B9', '\u00BA', '\u00BB', '\u00BC', '\u00BD', '\u00BE', '\u00BF',
        /* C0 */ '\u00C0', '\u00C1', '\u00C2', '\u00C3', '\u00C4', '\u00C5', '\u00C6', '\u00C7', '\u00C8', '\u00C9', '\u00CA', '\u00CB', '\u00CC', '\u00CD', '\u00CE', '\u00CF',
        /* D0 */ '\u00D0', '\u00D1', '\u00D2', '\u00D3', '\u00D4', '\u00D5', '\u00D6', '\u00D7', '\u00D8', '\u00D9', '\u00DA', '\u00DB', '\u00DC', '\u00DD', '\u00DE', '\u00DF',
        /* E0 */ '\u00E0', '\u00E1', '\u00E2', '\u00E3', '\u00E4', '\u00E5', '\u00E6', '\u00E7', '\u00E8', '\u00E9', '\u00EA', '\u00EB', '\u00EC', '\u00ED', '\u00EE', '\u00EF',
        /* F0 */ '\u00F0', '\u00F1', '\u00F2', '\u00F3', '\u00F4', '\u00F5', '\u00F6', '\u00F7', '\u00F8', '\u00F9', '\u00FA', '\u00FB', '\u00FC', '\u00FD', '\u00FE', '\u00FF'
    };
}
